Leather-like material and method of making the same



United States Patent 3,223,551 LEATHER-LIKE MATEREAL AND METHOD OFPVIAKHNG THE SAME Shu-Tung Tu, Ipswich, Mass., assignor to United ShoeMachinery Corporation, Flemington, N.J., a corporation of New Jersey NoDrawing. Filed Feb. 5, 1963, Ser. No. 256,225

Claims. (Ci. 117-140) This application is a continuation-in-part of mycopending application Serial No. 170,225, entitled Leather-Like Materialand Method of Making the Same, which was filed January 31, 1962, and isnow abandoned.

This invention relates to a strong leather-like material and to a methodof making the same.

In my earlier application Serial No. 94,999, filed August 24, 1961,entitled Processes of Making Leather-Like Materials, and now abandoned,there is disclosed the manufacture of a leather-like material in whichan aqueous slurry of collagen fibers is formed into a wet web bystraining the water from the slurry through a foraminous surface,introducing a gelatin or collagen solution into the web and treating theweb for example, with a chromium tanning agent to convert the gelatin orcollagen material to insoluable state in which it holds the collagenfibers in open-fibered leather-like relation after removal of theremaining water. The resulting sheets possess many of thecharacteristics of leather including excellent water vapor transmission,warmth, feel and so on.

It is an object of the present invention to form a sheet havingcomparable properties but having superior strength and to provide asimple method for making this sheet material.

To this end, and in accordance with a feature of the present invention,1 have devised a process for associating undissolved collagen with amass of intermeshed fibers as a fiber structure extending through themass in a relation in which the collagen fiber structure holds theintermeshed fibers against major displacement to give a novel producthaving high strength coupled with the moisture vapor transmission andabsorption characteristics of col lagen fibers and a warmth and handcomparable to leather.

I have found that lightly tanned collagen suspended under specialconditions in an aqueous medium as distinct, slightly swollen fibers ofmicroscopic size will remain in suspension for penetration ofintermeshed fibrous masses. Thereafter by altering the conditions thefibers are deswelled and associated with each other as a larger collagenfiber structure extending through the fiber masses and associated withthe fibers of the masses to reinforce them against displacement. Thenovel reinforced fiber masses are strong and possess many of thecharacteristics of leather.

The microscopic fiber suspension used in the present process is aspecial material from the special treatment of the collagen material.The collagen source, for example, skin or hide, is beaten underconditions which limit swelling of the collagen into fibers ofmicroscopic size to form a suspension in which the fibers are capable ofrelatively free movement in the aqueous medium in which formed. Thecondition is markedly different from that referred to as colloidal inwhich collagen is reduced to a swollen viscous mass.

A suspension of collagen microscopic fibers useful in the presentprocess may be formed by beating skin material in an aqueous medium. Inthis procedure, skin material preferably is lightly tanned for example,to an extent comparable to to preferably not over 3% of combinedaldehyde such as formaldehyde, glutaraldehyde, or glyoxal based on thedried weight of the skin material to bring the skin material to acondition in which 3,223,551 Patented Dec. 14, 1965 it can best bereduced by beating in water under controlled pH conditions to itsseparate fibers. From about 1% to about 8% by weight of small skinpieces is placed in water in a beater similar to a paper beater andbeating is carried out at a pH of from 2 to 8. Beating at pH 5 to 8 ispreferred since the fibers obtained in this range show a special changeto a shortened condition favorable to penetration into fiber batts whenbrought to penetration pH values. Also there are marked advantages inease of beating and avoidance of degradation of the collagen.

The tendency to swelling of skin material in an aqueous medium increasesas the departure of the pH of the medium from the isoelectric range ofthe skin material increases. The tendency to swelling is reduced as theextent of tanning, e.g., the aldehyde content increases. The swelling isalso dependent on the collagen swelling property of the pH control agentused. For example, sulfuric acid is a lightly swelling acid while formicacid, phosphoric acid, acetic acid and citric acid are strong swellingacids. Best results for purposes of the present invention are secured bybalancing these factors to bring the skin or hide to the condition ofincipient swelling so that the bonds between fibers are weakened but thefibers are separable as distinct elements.

For purposes of the present invention, a suspension of microscopicdistinct fibers may be prepared from skin material, preferably lightlytanned by controlling the pH in the beater relative to extent of tanningand the collagen swelling character of the pH control agent to giveincipient swelling. The beating of the skin material is carried to anextent to form distinct non-colloidal fibers which have a length of fromabout .001 mm. to not over about 4 mm. in length and preferably not over1 mm. in length. If desired the beating may be carried out in stages toform first coarse fibers which optionally may be separated from thebeater water, introduced into further water and then subjected tofurther beating to form fine fibers. The suspension obtained by beatingin the preferred range of from pH 5 to pH 8 is white and opaque. Ifspread on the surface of a batt of fibers, it remains substantially onthe surface allowing the water content to drain through the fiber battleaving a crusty deposit of the fibers on the surface.

I have found, however, that by subjecting the collagen fibers insuspension to controlled swelling conditions, the fibers of thesuspension will penetrate into the interstitial spaces of a fiber battand will be retained by the fibers of the batt so that the batt is.filled through and through with the dispersion. The term swelling in thespecial sense here intended refers to the phenomenon that the surfacesof the fibers become slippery and the fibers increase in thickness anddecrease in length but remain as distinct fibers. The suspension losesits whitish opacity, becomes translucent and increases in viscosity.

The extent to which collagen fibers in suspension are brought to acondition for effective penetration into an intermeshed fiber mat varieswith the formaldehyde content and with the pH. With a given collagenfiber, penetration ability will increase from a minimum adjacent theisoelectric range along a. curve which peaks at about pH 2.0 on the acidside and at about pH 11.5 on the alkaline side of the isoelectric rangeand falls off on either side of the peaks.

A useful degree of swelling is obtainable at pH values about 0.5 of a pHunit outside the isoelectric range of the collagen fiber. Where thecollagen fiber is obtained from hid-es which have been limed, theisoelectric range may be from about 4 to 5.5 while with hides which havenot been limed the isoelectric range may be from about 7 to about 8.Ordinarily limed hides which are more readily available will be used andthe following descriptiontion sets forth conditions particularly usefulwith fibers from limed hides. Adjustment of pH values for use withfibers from other hides can be made readily by chemists. On the acidside of the range the pH of the suspension of collagen fiber from limedhide will ordinarily be kept in the range of from about pH 0.5 to aboutpH 3.5 and most desirably from about pH 2 to about pH 3.0. The higherportions of this range are used with the more highly swelling acids suchas formic acid, acetic acid, citric acid, phospheric acid and others.

Effective swelling above the isoelectric range has been obtained in asuspension of collagen fiber from limed hide at a pH in the range offrom about pH 6.0 to about pH 12 and more desirably from about pH 8 toabout pH 10. The fiber suspension may be brought to this range byaddition of alkaline reagents such as sodium hydroxide, tri-sodiumphosphate, potassium hydroxide and various other alkaline hydroxides andsalts which do not form insoluble compounds with the collagen.

The collagen fiber dispersions having pH values above the isoelectricrange offer certain advantages over the acidic collagen fibersuspensions. An important factor is that on the alkaline side, theproperties of the collagen fiber slurry remain fairly constant onstorage, while on the acid side there may be a progressive loss oftanning agent particularly where formaldehyde is the tanning agent sothat the properties of a fiber suspension on the acid side change onstorage, apparently due, at least partially, to loss of formaldehydefrom the fiber. Additionally, many synthetic resin and synthetic rubberpolymer and copolymer emulsions or latices are at least mildly alkalineand may be admixed to the alkaline collagen fiber suspension withoutdifficulty, while addition of such alkaline materials to an acidcollagen fiber suspension would result in coagulation of the syntheticresin or synthetic rubber emulsion and/or precipitation of the collagenfibers from suspension. With the alkaline collagen fiber suspensionsthus, it is possible to include synthetic rubber or synthetic resinadditionally to modify the properties of the final product. Also otheralkaline emulsions, for example, fat liquor emulsions and liquidsolutions or suspensions of various dyes or pigments may be included.

The extent of tanning of the hide material as with formaldehyde has beenfound to be an important factor in the bringing of the collagenmicroscopic fiber suspension into the desired state for effectivepenetration and retention of the dispersed fibers within the batt.Penetration ability decreases and retention of the fiber increases withincrease in the extent of tanning. It has been found generally desirableto use collagen fiber tanned to an extent corresponding to about 0.2% toabout 1.1% formaldehyde by weight based on the weight of the collagenfiber. Thus, it has been found that with a formaldehyde content of 0.2%by weight based on the weight of the hide material, the fiber suspensionat the important pH range penetrates well into a given fiber batt butthat retention of the fibrous material in the batt is barely acceptable.Where the formaldehyde content is 1.1% by weight based on the weight ofthe hide material, a proportion of the fibers may be retained on thesurface of the same fiber batt to which the suspension is applied andthe penetration properties are poor. Within this range and preferably ata formaldehyde content of from about 0.4 to about 0.6% by weight basedon the weight of the hide material the suspension penetrate-s well andthe fibers are retained effectively Within the fiber batt. It isimportant that the fibers have been swollen to a controlled degree foreffective use and it is believed that one effect of this swelling is aplasticizing of the fibrous collagen material enabling the fibers tomove effectively through the interstices in the fiber batt. Highertanning agent contents restrain the extent of swelling to reduce theability of the fibrous material to enter the batt and if no tanningagent is used, there is not only an undesirable increase in viscositywhich makes it difficult to use it to penetrate a fiber batt but thefibrous material is not retained well by the fibers of the batt.

There is some indication that, at least with the more highly tannedcollagen fibers, for example, fibers containing from about 0.6% to about0.8% by Weight formaldehyde based on the weight of the fibers, theswelling may occur primarily at the surfaces of the fibers. This offersthe advantage that the fibers develop a surface character allowing thefibers to slip relative to one another and to the fibers of the mat tobe impregnated so that the fibers will penetrate a fiber mat, while thevolume of individual fibers is not greatly increased so that theultimate quantity of collagen fiber solids on a dry fiber basis whichcan be introduced into a mat to fill the interstitial spaces in the matmay be greater with the more highly tanned fibers than with the lesstanned fibers.

Where a collagen fiber suspension in which the collagen has a hightanning agent content for example, 1.1% of formaldehyde which ordinarilywould penetrate poorly with a substantial portion retained on thesurface of a given fiber batt, is blended for example, in the range ofratios of from 2:1 to 1:2 parts by weight with a low aldehyde contentcollagen fiber suspension for example, one having a 0.1% to 0.4%formaldehyde content, the resulting mixtures, which will haverespectively .8 and .65 formaldehyde by weight, penetrate the fiber batteffectively and are retained effectively within the fiber batt. Althoughapplicant does not wish to be bound by the theory, it appears that thelow formaldehyde content fibers serve as a carrier for the highformaldehyde content fibers to aid in penetration. On the other hand,the high form-a1- dehyde content fibers impart to the mixture thedesired retention characteristics. Because of the importance ofmaintaining the formaldehyde content within the range useful at theselected pH, the ability to abjust the formaldehyde content by additionof high formaldehyde or low formaldehyde content fiber suspension is ofconsiderable practical value. The carrier action of the low formaldehydecontent fibers may also be used to enable penetration of a suspension ofchrome tanned collagen microscopic fibers or other fine fibers such asnylon, polyester, rayon and others into a fiber batt. Thus, a suspensionof microscopic fibers of collagen having a chromium content of from 0.5%to 4% by weight calculated as Cr O based on the weight of the collagenmay be combined with a suspension of microscopic collagen fibers havingan aldehyde content of from 0.17% to 0.4% based on the weight of thecollagen in the range of ratios of from 2:1 to 1:2 to form a mixedsuspension with useful penetration and retention properties.

Suspensions in which the collagen fiber has a relatively highformaldehyde content and relatively poor penetnation into a fiber may beimproved in this respect by adding a solution of gelatin to thissuspension. pnovement has been obtained with addition of as little asone part of gelatin to 10 parts of the microscopic collagen fibers, andas much as one part of gelatin to one part of microscopic collagenfibers may be used.

An addition of a cationic or anionic surface active agent, depending onwhether the slurry is acidic or basic, to a suspension of microscopiccollagen fibers having poor penetration characteristics is alsoeffective to improve the penetration of the suspension into a fiber.This effect is obtainable with as little as 1% based on the Weight ofthe collagen fiber in suspension.

The ability of fibers to penetrate a mat depends also on the retainedopenness of a mat during application of the collagen fiber slurry orsuspension. Fiber mats which retain a high degree of openness may bepenetrated with collagen fiber suspensions with a degree of tanning andunder pH conditions giving a relatively low penetrating ability whichwould not effectively enter less open fiber mats. It is possible to formfiber mats filled with collagen fibers by adjusting the penetratingability of the collagen fiber suspension through control of extent oftanning and Noticeable impH conditions relative to the retained opennessof the fiber mat.

In addition to the factors of extent of tanning and pH control whichexert a primary effect on the penetration ability, it has been foundthat a limited control over penetrating ability can be obtained byadjusting the collagen fiber solids content of a suspension. That its,suspensions of collagen fibers with relatively low penetrating abilitymay penetrate more effectively where the collagen fiber \solids contentis reduced to a relatively low percentage. Suspensions having collagenfiber solids contents of at least 0.5% preferably from about 1% to about5% are preferred from the standpoint of securinga good penetration andthe introduction of a desired high collagen fiber solids content into afiber mat with desirable eificiency in time and amount of suspensionhandled. It will be understood that it is possible to operate somewhatoutside these ranges; but, for example, the use of a lower solidscontent suspension entails the separation of collagen fiber from a largevolume of liquid; and use of a higher solids content suspension mayrequire an undesirably open mat or result in uneven penetration.

When the pH of a collagen fiber suspension in which controlled swellinghas been produced as above described, approaches or reaches theisoelectric range, there is an observable association of the fibers intosubstanially aligned relationship. It appears that as association of theindividual fibers proceeds, a larger collagen fiber structure isreaggregated from a multitude of the microscopic fibers and iscomparable to native larger collagen fibers. This association which isbelieved to be of a physical-chemical nature is what is referred toherein as reaggreg-ation and is a phenomenon different from thereconstitution of collagen from solution on the one hand and from thecementing together of colloidal collagenous material on the other hand.Itis to be noted with particular respect to the heretofore knownprocesses for extruding swollen or colloidal material that there it hasbeen found necessary to induce an orientation of the collagenousmaterial by stretching for example, an extruded filament. In the presentcase, on the other hand, it appears that the collagen microscopic fibersare able to align and orient themeselves under the influence of theelectrical charges in the microscopic fibers by reason of the relativefreeness of the fibers in the liquid phase so that the advantages of anoriented fibrous material are obtainable under conditions existing in afibrous batt where stretching to induce orientation is not possible.

The above discussion is advanced as of assistance in understanding theinvention but it is to be understood that patentability is not dependenton the correctness of the explanation advanced on the observedphenomena.

A wide variety of intermeshed fiber materials both Woven and nonwovenmay be used for association with collagen microscopic fiber suspensions.Ordinarily non- Woven fiber materials are preferred because of theirgreater variety of thicknesses, densities and openness to penetration bythe suspensions. Thus, the fibers may be nylon, polyacrylic ester fibers(Orlon), polyester fibers (Dacron), polypropylene fibers, Wool, extrudedcellulosic fibers such as viscose or cellulose acetate and others. Ithas been found that best results are secured when the fibers arehydrophobic. In this connection a batt of longer collagen fibrousmaterial which has been treated for example, by chrome tanning or othertreatment to decrease its affinity for water may be used. Also naturalcotton fiber preferably treated to decrease its affinity for water isalso usable.

Since an important aspect of the present invention is the manufacture ofleather-like products, the intermeshed fiber materials are preferably inthe form of relatively thin batts in which the fibers are in a relationproviding relatively large interstitial spaces. The fiber battspreferably although not necessarily have been subjected to a treatmentas with barbed needles to improve the intermeshing of the fibers. Afiber density and relation which have been found very satisfactory arethose in nylon fiber batts having densities of the order of 4 oz. persq. yd. at a thickness of 0.15" and 6 oz. per sq. yd. at a thickness of0.175". It is preferred that the fibers be relatively fine and fall inthe range of from 1 to 5 denier with 3 denier being satisfactory.Another highly satisfactory material is a polypropylene fiber batthaving a density of 7 oz. per sq. yd. and a thickness of 0.2".

Penetration of the suspension of swollen collagen microscopic fibersinto an intermeshed fiber mass may be effected in a variety of ways.Thus, a fiber batt may be immersed in a suspension, suitably arelatively low solids suspension of the order of 1% to 3% by weightsolids. The rate of impregnation may be increased by use of a vibrator.Another procedure involves disposing the fiber batt on a screen andforcing the suspension in with the aid of pressure or suction.Suspensions having a solids content of for example, from about 1% toabout 5% by weight solids may be used in this procedure. Still otherprocedures are available including spreading the suspension on thesurface of the batt and working it in.

Products having a higher collagen content at the surface may be formedby first treating the fiber batt with a collagen suspension having goodpenetrating ability and thereafter treating the batt with a suspensionhaving a lower penetration ability. If desired suspension may be appliedfrom alternate sides.

Reduction of the acid or alkali content of the collagen microscopicfiber material within a fiber mass and removal from the fibers of theWater of swelling may be effected by subjecting the fibrous. mass toextraction with distilled Water or a water miscible volatile organicsolvent such as acetone and other ketones, and lower alcohols such asmethanol, ethanol and isopropanol to bring the pH to the isoelectricrange. Treatment of the fiber batt with an aqueous solution of a buffersalt such as an acetate or phosphate buffer system is also effective tobring the pH to a value in the range of about 3.5 to about 6 at whichreaggregation of the collagen microscopic fibers will occur with removalof the swelling water from the fibers. It is desirable in the use ofbuffer systems to use a solution having an ionic strength of about 0.2.Reaggregation may also be effected by treating the fiber batt with a 10%aqueous ammonium sulfate solution which effects a deswelling of thefibers.

The fiber batt is compacted and reduced in thickness in the course ofpenetration by the suspension and reaggregation of the collagen materialso that, for example, starting with a 4 oz. per sq. yd. nylon fiber battwith an initial thickness of 0.15", after penetration by suspension andreaggregation of the collagen material, the thickness will have reducedto from about .015 to about .03. Correspondingly a sheet prepared from a6 oz. per sq. yd. nylon batt having an initial thickness of 0.175 willform a sheet about 0.04 inch in thickness. This reduction in thicknessis due in considerable measure to the action of the suspension in beingforced into the batt. A further action which influences the reduction inthickness is the pulling together of the collagen material by waterbonding; and this factor may range from very slight where water isextracted from the sheet by solvent to relatively large where asubstantial portion of the water is removed by evaporation.

The sheet material is preferably subjected to tanning with mineraltanning agents such as chrome tanning liquors or with vegetable tanningagents. Because of the collagen dcswelling action of mineral tanningagents such as chrome tanning agents it is possible to effect bothreaggregation and tanning with such agents. Conventional leather tanningprocedures may be used and the tanning may be carried out either in anaqueous tanning medium or a solvent type tanning medium.

After tanning the sheet material will be washed and pressed to removeexcess Water. Ordinarily the sheet is subjected to a treatment tointroduce a plasticizing or softening agent into it as by fat liquoringor preferably by immersing it in an acetone solution containing forexample, 4% by weight of oleic acid. After this treatment, the sheet isdried in air and may be subjected to various finishing treatmentsincluding the step of needling comparable to the needling of thecollagen fiber sheet material described in an application Serial No.805,032, now US. Patent 3,073,7l4,issued January 15, 1963, and entitledImproved Collagen Fiber Sheet Material, filed April 8, 1959, in thenames of the present inventor and John H. Highberger.

For use, the surface of the sheet may be coated with leather finishes orresinous and/or waxy material. A preferred finish for the sheet materialinvolves the application to the surface of the sheet of certain soluble,800 type, nylons (which are alkoxy derivatives of type 66 nylon) whichare believed to contain groups reactive with certain groups of thecollagen material. Formation of this coating may involve a deposition asby spraying of a solution of a suitable nylon in a 70% isopropanolsolution, this solution suitably containing pigment to give the desiredcolor. After the solution is applied the sheet is dried, subjected to aneedling treatment, and thereafter embossed or plated. The surface soobtained is a soft, strong and flexible film closely resembling thegrain surface of leather and firmly adherent to the sheet.

The following examples are given to aid in understanding the inventionand it is to be understood that the invention is not restricted to theparticular materials, proportions or procedures set forth therein:

Example I Pickled belly split was Washed and 35 lbs. of the washedmaterial was introduced into a drum along with a buffer rnade of: 1200ml. of glacial acetic acid, 1000 gms. of sodium hydroxide and 1000 ml.of a 37% solution of formaldehyde and 80 lbs. of water. The drum wasrotated for 21 hours and the splits were then drained, washed for onehour, hosed and drained for /2 hour and then cut into approximately oneinch pieces. The formaldehyde content of the material at this time wasabout 0.85% by weight based on the weight of the dry collagen. Thechopped material was introduced into a Hollander type paper beater andmade up to a 200 lb. batch by addition of water. The pH of the materialin the beater at this time was about 5.4. The beater was operated until4 kw. hours of energy had been supplied to the beating operation. Atthis time 250 cc. of an emulsifying agent were added and beatingcontinued for three minutes. This beating emulsified the fat content ofthe split material and the resulting emulsion was drained off. Half ofthe split material was put back in the beater along with 80 lbs. ofwater and the beating continued. The pH of the material was adjusted toapproximately pH 7 by additions of a 4 N solution of sodium hydroxide.After 4 /2 hours of beating, the material was reduced to a suspension ofcollagen fibers having a length of from about 0.2 to about 1 mm. Thesuspension was diluted by addition of water to bring the solids contentto about 2%, and had a viscosity at 20 C. of 1250 centipoises. Thesuspension was acidified in the beater by addition of phosphoric acid tobring the pH to about 2.3 and its viscosity increased to about 5000centipoises.

A rectangular sheet 18 inches by 12 inches of nylon fiber batt having aweight of 6 oz. per sq. yd., a thickness of 0.175 inch and a fiberdenier of 3 was disposed on a filter bed provided with means forapplying suction. A quantity of the above prepared fiber suspension wasdeposited on the fiber batt, leveled with a rubber squeegee. Suction wasapplied which pulled the suspension into the batt, the liquid leavingthe batt being a relatively fiber-free material. The resulting sheet hada collagen fiber content of about 50% based on the dry weight of thesheet. Six liters of dry acetone were then drawn through the batt toremove water and to effect a reaggregation of the microscopic fibers ofthe suspension. This acetone is added in two portions of which the firstportion consisting of 4 liters is drawn through immediately and the lasttwo are allowed to stand on the surface of the treated batt for 10minutes and then drawn through.

The resulting sheet material after removal from the filter resembled asolvent dried skin material and was subjected to tanning by immersionfor /2 hour in a standard buffered chromium tanning liquor containing0.5% chronium calculated as Cr O and 1% of sodium formate and having apH of 4. The sheets were then removed from the tanning liquor andallowed to stand overnight in a covered receptacle; the sheets were thenwashed in water for three successive periods of 15 minutes.

After washing the sheets were dried by immersion in successive acetonebaths and the dried sheets were then immersed in a 4% by weight solutionof oleic acid in acetone for 1 /2 hours. Thereafter the sheets wereremoved and allowed to dry at room temperature. The dried sheets weresimilar to a chromium tanned skin and its physical properties were inthe range of leather.

A coating solution was prepared by combining the following ingredientsand beating in a Waring Blendor at 40 to 45 C. for from 20 to 25minutes.

The above solution was cooled and sprayed in several pieces on the driedsheets and the sprayed sheets were then dried in an oven at 150 F. forthree hours.

The dried sheets were subjected to a needling operation to provide about1500 perforations per sq. inch. Thereafter the sheet was plated at 250F. and 500 pounds per sq. inch pressure for about 15 seconds.

The finished sheet resembled a good grade of leather suitable for shoemanufacture.

Example ll Limed hide was delimed and washed to remove salts. Fiftypounds of the wet hide (15% dry hide solids) was put in a tanning bathcomprising pounds of water, 1.6 liters of glacial acetic acid, 1000grams of sodium hydroxide and 1000 ml. of 37% formaldehyde. The pH ofthe bath was about 5. After 16 hours the hide was removed, washed anddrained. The formaldehyde content was about 0.4% by weight. The hide wasthen chopped into /1, inch pieces and introduced into a Hollander alongwith water in amount to make the hide solids content about 6%. After 15minutes beating in the Hollander a small amount of a wetting agent wasadded and beating continued for about 5 minutes. The resultingsuspension of fiber was drained and then squeezed between rollers toremove further water. The fiber was returned to the Hollander togetherwith water to make the solids content about 6%. The pH was adjusted toabout 7 and the Hollander operated for four hours. At the end of thetime the hide material had been teased into microscopic fibers uniformlysuspended in the water. The suspension was diluted by addition of waterto bring its solids content to about 1.5% and the suspension was madealakaline in the beater by addition of sodium hydroxide to bring its pHto 8.59.

A rectangular sheet 18" x 12" of nylon fiber batt having a weight of 7ounces per square yard, a thickness of 9 r 0.175" and a fiber denier of3 was disposed on a filter bed provided with means for applying suction.

Four liters of the fiber suspension was deposited on the fiber batt andleveled with a rubber squeegee and pulled into the batt by applicationof suction. Five minutes were required to pull the suspension into thebatt. The resulting sheet had a collagen fiber content of about 42.7%based on the dry weight of the sheet. The sheet was treated withacetone, tanned and dried as in Example I. On examination it was foundthat the fiber had penetrated unformly through the sheet and that thephysical properties of the sheet were in the range of leather.

Example III A suspension of collagen fiber was prepared by proceduressimilar to that set forth in Exchange II, but using only 700 ml. of theformaldehyde solution to provide a formaldehyde content combined withfiber of 0.18% by weight based on the weight of the dry collagen. Afterthe beating step, the suspension was diluted by addition of water tobring its solids content to about 1.5% and the suspension was madealkaline in the beater by addition of sodium hydroxide to bring its pHto 9.4.

A rectangular sheet 18" x 12" of nylon fiber batt having a weight of 7ounces per square yard, a thickness of 0.175" and a fiber denier of 3was disposed on a filter bed provided with means for applying suction.

Three liters of the fiber suspension was deposited on the fiber batt ona level with a rubber squeegee and pulled into the batt by applicationof suction over a period of about five and one-half minutes. Theresulting sheet had a collagen fiber content of about 38.1% based on thedry weight of the sheet. The sheet was treated with acetone, tanned anddried as in Example I. On examination it was found that the fiber hadpenetrated uniformly through the sheet and that the physical propertiesof the sheet were in the range of leather.

Example IV A collagen fiber suspension was prepared as in Example II tohave a formaldehyde content combined with fiber of 0.41% by weight basedon the weight of the dry collagen. The suspension was diluted with waterto bring the solids content to about 1.0% and adjusted by addition ofsodium hydroxide to bring its pH to 11.0.

A rectangular sheet 18" x 12" of polypropylene fiber batt having aweight of 7 ounces per square yard, a thickness of 0.190 and a fiberdenier of 3 was disposed on the filter bed and 4 liters of thesuspension was deposited on the fiber batt and leveled with a rubbersqueegee. Suction was applied to pull the suspension into the batt.After 1% minutes, all of the suspension had been pulled into the batt.The resulting sheet had a collagen fiber content of about 34.6% based onthe dry weight of the sheet. The sheet was treated with acetone anddried as in Example I. On examination of the sheet it was found that thecollagen fibers were distributed through the batt with a fair degree ofuniformity.

Example V 6 Using the same fiber suspension as in Example IV andfollowing the procedure of Example 1V but after a days storage of thesuspension, it was found that the suspension was pulled into the batt in1 minute and that the resulting sheet had a collagen fiber content of37.2% based on 6 the dry weight of the sheet. Also, the collagen fiberwas distributed more uniformly through the sheet.

Example VI A further portion of the collagen fiber suspension pre- 7pared in Example IV was adjusted to a pH of 7.3 and four liters of thissuspension was disposed on a nylon fibers batt having a weight of 7ounces per square yard and a fiber denier of 3 on a filter bed. Suctionwas applied to pull the suspension into the batt. Three and 7 1.0one-half minutes were required to pull the liquid into the batt. Theresulting sheet was treated with acetone and tanned in accordance withthe procedure of Example I. On examination it was found that theresulting sheet had a collagen fiber content of about 43.1% based on thedry weight of the sheet and the collagen material was distributeduniformly throughout the sheet.

Example VII The procedure of Example VI was repeated with the fibersuspension at a pH of 6.55. The suspension had been pulled into thefiber batt in 1% minutes and the resulting sheet had a collagen fibercontent of 50.2% based on the dry weight of the sheet. On examination ofthe tanned sheet it was found that the fiber distribution was not asuniform as in Example VI and that there was a markedly higherconcentration of fiber adjacent the surface of the sheet on which thesuspension had initially been disposed.

Example VIII The collagen fiber slurry of Example IV was diluted to 0.5%solids. When deposited on a 7 ounce per square yard nylon fiber batt(fiber denier of 3) it was found that the slurry would penetrate thefiber batt at pH of 2.7 and below, that it would not penetrate at valuesin the range of 2.75 to 6.80 and that it would penetrate effectively atpH 7.35 and above.

Using a polypropylene fiber batt having a weight of 7 ounces per squareyard and a fiber denier of 3 it was found that the suspension wouldpenetrate the fiber batt at pH of 3.09 and below, that it would notpenetrate at pH values of from 3.10 to 6.08 and that it would penetrateeffectively at pH of 6.55 and above.

Using a polypropylene fiber batt having a weight of 2 /2 ounces persquare yard and a fiber denier of 3, it was found that the suspensionwould penetrate the fiber batt at pH of 3.0 and lower, that it would notpenetrate the batt at pH values in the range of 3.3 to 5.8 and that itwould penetrate effectively at pH values of 6.10 and above.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. The process of forming a leather-like material which comprises thesteps of applying to an intermeshed fiber mass in penetrating relationan aqueous suspension containing from about 1% to about 5% by weightbased on the weight of the suspension of swollen distinct fine collagenfibers of microscopic size to carry said collagen fibers into theinterstitial spaces of said intermeshed fiber mass, said suspensionhaving a pH outside the isoelectric range of said collagen fiber,removing the swelling water from said fine short collagen fibers in theinterstitial spaces of said intermeshed fiber mass to reaggregate theminto a larger collagen fiber structure within the interstitial spacesthroughout said mass of intermeshed fibers to reinforce said intermeshedfibers against displacement.

2. The process of forming a leather-like material which comprises thesteps of applying to an intermeshed fiber mass in penetrating relationan aqueous suspension containing from about 1% to about 5% by weightbased on the weight of the suspension of swollen distinct fine shortcollagen fibers from about .001 mm. to about 4 nun. in length to carrysaid collagen fibers into the interstitial spaces of said intermeshedfiber mass, said suspension having a pH outside the isoelectric range ofsaid collagen fiber and a content of aldehyde chemically combined withsaid collagen fibers of from about 0.1% to about 3.0% based on the dryweight of said collagen fibers, said suspension being applied inquantity sufiicient to provide from about 5% to about 90% by weight ofcollagen fibers within the spaces in said intermeshed fiber mass basedon the combined weight of said intermeshed fibers and the collagenfibers, adjusting the pH of the suspension of said collagen fibers insaid intermeshed fiber mass to the isoelectric range of said collagenfiber and removing the swelling water from said'fine short collagenfibers in the interstitial spaces of said intermeshed fiber mass toreaggregate them into a larger collagen fiber structure within theinterstitial spaces throughout said mass of intermeshed fibers toreinforce said intermeshed fibers against displacement.

3. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penetratingrelation an aqueous suspension containing from about 1% to about byweight based on the weight of the suspension of swollen distinct fineshort collagen fibers from about .001 mm. to about 4 mm. in length tocarry said collagen fibers into the interstitial spaces of saidintermeshed fiber mass, said suspension having a pH of from about 0.5 toabout 3.5 and a content of aldehyde chemically combined with saidcollagen fibers of from about 0.1% to about 3.0% based on the dry weightof said collagen fibers, said suspension being applied in quantitysutficient to provide from about 5% to about 90% by weight of collagenfibers within the spaces in said intermeshed fiber mass based on thecombined weight of said intermeshed fibers and the collagen fibers,reducing the acid content of the suspension in said fiber mass to bringthe pH to and maintain the pH at from about 3.5 to about 7.0 andremoving the swelling water from said fine short collagen fibers in theinterstitial spaces of said intermeshed fiber mass to reaggregate theminto a larger collagen fiber structure within the interstitial spacesthroughout said mass of intermeshed fibers to reinforce said intermeshedfibers against displacement.

4. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penetratingrelation a mixture of a synthetic polymeric latex and an aqueoussuspension containing about 1% to about 5% by weight based on the weightof the suspension of swollen distinct fine short collagen fibers fromabout 0.001 mm. to about 4 mm. in length to carry said collagen fibersinto the interstitial spaces of said intermeshed fiber mass, saidmixture having a pH at least about 0.5 of a pH unit outside the isoelectric range of said collagen fiber and said collagen fiber having acontent of chemically combined aldehyde of from about 0.1 to about 3.0%based on the dry weight of said collagen fibers, said mixture containingfrom about 5% to about by weight of synthetic polymer solids based onthe weight of said collagen fibers, said suspension being applied tosaid intermeshed fiber mass in quantity sufiicient to provide from about5% to about 90% by weight of collagen fibers within the spaces in saidintermeshed fiber mass based on the combined weight of said intermeshedfibers and the collagen fibers, adjusting the pH of the mixture in saidintermeshed fiber mass to the isoelectric range of said collagen fiberand removing the swelling water from said fine short collagen fibers inthe interstitial spaces of said intermeshed fiber mass to reaggregatethem into a larger collagen fiber structure within the interstitialspaces throughout said mass of intermeshed fibers to reinforce saidintermeshed fibers against displacement.

5. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penetratingrelation an aqueous alkaline suspension containing from about 1% toabout 5% based on the weight of the suspension of swollen distinct fineshort collagen fibers from about .001 mm. to about 4 mm. in length tocarry said collagen fibers into the interstitial spaces of saidintermeshed fiber mass, said suspension having a pH of from about pH 6to about pH 12 and a content of aldehyde chemically combined with saidcollagen fibers of from about 0.1% to about 3% based on the dry weightof said collagen fibers, said suspension being applied in quantitysuificient to provide about 5% to about by weight of collagen fiberswithin the spaces in said intermeshed fiber mass based on the combinedweight of said intermeshed fibers and the collagen fibers, reducing thealkali content of the suspension in said fiber mass to bring the pH tofrom about 3.5 to about 6.0 and removing the swelling water from saidfine short collagen fibers in the interstitial spaces of saidintermeshed fiber mass to reaggregate them into a larger collagen fiberstructure within the interstitial spaces throughout said mass ofintermeshed fibers to reinforce said intermeshed fibers againstdisplacement.

6. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penetratingrelation a mixture of a synthetic polymeric latex and an aqueousalkaline sus pension containing about 1% to about 5% by weight based onthe weight of the suspension of swollen distinct fine short collagenfibers from about 0.001 mm. to about 4 mm. in length to carry saidcollagen fibers into the interstitial spaces of said intermeshed fibermass, said mixture having a pH of from about pH 8 to about pH 10, andsaid collagen fiber having a content of chemically combined aldehyde offrom about 0.1 to about 3.0% based on the dry weight of said collagenfibers, said mixture containing from about 5% to about 20% by weight ofsynthetic polymer solids based on the weight of said collagen fibers,said suspension being applied to said intermeshed fiber mass in quantitysufficient to provide from about 5% to about 90% by weight of collagenfibers within the spaces in said intermeshed fiber mass based on thecombined weight of said intermeshed fibers and the collagen fibers,reducing the alkali content of the mixture in said intermeshed fibermass to bring the pH to from about 3.5 to about 6.0 and removing theswelling water from said fine short collagen fibers in the interstitialspaces of said intermeshed fiber mass to reaggregate them into a largercollagen fiber structure within the interstitial spaces throughout saidmass of intermeshed fibers to reinforce said intermeshed fibers againstdisplacement.

7. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penteratingrelation an aqueous acidic suspension containing from about 1% to about5% by weight based on the weight of the suspension of swollen distinctfine short collagen fibers from about .001 mm. to about 4 mm. in lengthto carry said collagen fibers into the interstitial spaces of saidintermeshed fiber mass, said suspension having a pH of from about 2 to 3and comprising a mixture of collagen fibers tanned to so high an extentthat the suspension has poor penetration ability and collagen fibershaving a chemically combined aldehyde content of from about 0.4% toabout 0.6% by weight based on the dry weight of the fibers, the collagenfibers of said mixture being combined in the ratio of from about 1:2 toabout 221 based on the dry weight of the collagen fibers in saidsuspension, said suspension being applied in quantity suflicient toprovide from about 5% to about 90% by weight of collagen fibers withinthe spaces in said intermeshed fiber mass based on the combined weightof said intermeshed fibers and the collagen fibers, reducing the acidcontent of the suspension in said fiber mass to bring and maintain thepH to from about 3.5 to about 6.0 and removing the swelling water fromsaid fine short collagen fibers in the interstitial spaces of saidintermeshed fiber mass to reaggregate them into a larger collagen fiberstructure within the interstitial spaces throughout said mass ofintermeshed fibers to reinforce said intermeshed fibers againstdisplacement.

8. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed fiber mass in penetratingrelation an aqueous acidic suspension containing from about 1% to about5% by Weight based on the weight of the suspension of swollen distinctfine short collagen fibers from about .001 mm. to about 4 mm. in lengthto carry said collagen fibers into the interstitial spaces of saidintermeshed fiber mass, said suspension having a pH of from about 2 to 3and comprising collagen fibers tanned to so high an extent that asuspension of such fibers has poor penetration ability and a cationicsurface active agent to improve the penetration ability of thesuspension, said suspension being applied in quantity s-utficient toprovide from about to about 90% by weight of collagen fibers Within thespaces in said intermeshed fiber mass based on the combined weight ofsaid intermeshed fibers and the collagen fibers, reducing the acidcontent of the suspension in said fiber mass to bring and maintain thepH to from about 3.5 to about 6.0 and removing the swelling water fromsaid fine short collagen fibers in the interstitial spaces of saidintermeshed fiber mass to reaggregate them into a larger collagen fiberstructure within the interstitial spaces throughout said mass ofintermeshed fibers to reinforce said intermeshed fibers againstdisplacement.

9. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed nylon fiber mass inpenetrating relation an aqueous acidic suspension containing from about1% to about 5% by weight based on the weight of the suspension ofswollen distinct fine short collagen fibers from about .001 mm. to about4 mm. in length to carry said collagen fibers into the interstitialspaces of said intermeshed fiber mass, said suspension having a pH offrom about 0.5 to about 3.5 and a content of formaldehyde chemicallycombined with said collagen fibers of from about 0.1% to about 3.0%based on the dry weight of said collagen fibers, said suspension beingapplied in quantity sufficient to provide from about 5% to about 90% byweight of collagen fibers within the spaces in said intermeshed fibermass based on the combined weight of said intermeshed fibers and thecollagen fibers, reducing the acid content of the suspension in saidfiber mass to bring and maintain the pH to from about 3.5 to about 6.0and removing the swelling water from said fine short collagen fibers inthe interstitial spaces of said intermeshed fiber mass to reaggregatethem into a larger collagen fiber structure within the interstitialspaces throughout said mass of intermeshed fibers to reinforce saidintermeshed fibers against displacement, said reduction of acid contentand removal of water being effected by treating said fiber mass with avolatile water-miscible organic solvent.

10. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven open-intermeshed nylon fiber sheet anaqueous acidic suspension containing from about 1% to about 5% by weightbased on the weight of the suspension of swollen distinct fine shortcollagen fibers from about .001 mm. to about 1 mm. in length to carrysaid collagen fibers into the interstitial spaces of said intermeshedfiber sheet, the fibers of said sheet having a denier of from 1 to 5,said suspension having a pH of from about 2 to 3 and a content offormaldehyde chemically combined with said collagen fibers of from about0.4% to about 0.6% based on the dry weight of said collagen fibers, saidsuspension being applied in quantity sufiicient to provide from about30% to about 50% by weight of collagen fibers within the spaces in saidintermeshed fiber sheet based on the combined weight of the nylon fibersof the sheet and the collagen fibers, reducing the acid content of thesuspension in said sheet to bring and maintain the pH to from about 3.5to about 6.0 and removing the swelling water from said fine shortcollagen fibers in the interstitial spaces of said intermeshed fibersheet to reaggregate them into a larger collagen fiber structure withinthe interstitial spaces between the nylon fibers throughout said sheetto reinforce the fibers of said sheet 14 against displacement, saidreduction of acid content and removal of water being efiected bytreating said sheet with a volatile water-miscible organic solvent.

11. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven intermeshed nylon fiber mass inpenetrating relation an aqueous acidic suspension containing from about1% to about 5% by weight based on the weight of the suspension ofswollen distinct fine short collagen fibers from about .001 mm. to about4 mm. in length to carry said collagen fibers into the interstitialspaces of said intermeshed fiber mass, said suspension having a pH offrom about 2 to about 3 and a content of formaldehyde chemicallycombined with said collagen fibers of from about 0.1% to about 3.0%based on the dry weight of said collagen fibers, said suspension beingapplied in quantity sulficient to provide from about 5% to about byWeight of collagen fibers Within the spaces in said intermeshed fibermeans based on the combined weight of said intermeshed fibers and thecollagen fibers, reducing the acid content of the suspension in saidfiber mass to bring and maintain the pH to from about 3.5 to about 6.0and removing the swelling water from said fine short collagen fibers inthe interstitial spaces of said intermeshed fiber mass to reaggregatethem into a larger collagen fiber structure Within the interstitialspaces throughout said mass of intermeshed fibers to reinforce saidintermeshed fibers against displacement, said reduction of acid contentand removal of water being effected by treating said fiber mass with avolatile water-miscible organic solvent, and thereafter tanning thecollagen fibrous material with a mineral tanning agent.

12. The process of forming a leather-like material which comprises thesteps of applying to a nonwoven open-intermeshed nylon fiber sheet inpenetrating relation an aqueous acidic suspension of swollen distinctfine short collagen fibers from about .001 mm. to about 1 mm. in lengthto carry said collagen fibers into the interstitial spaces of saidintermeshed fiber sheet, the fibers of said sheet having a denier offrom 1 to 5, said suspension having a pH of from about 2 to 3 and acontent of formaldehyde chemically combined with said collagen fibers offrom about 0.4% to about 0.6% based on the dry weight of said collagenfibers, said suspension being applied in quantity sufilcient to providefrom about 30% to about 90% by weight of collagen fibers within thespaces in said intermeshed fiber sheet based on the combined weight ofthe nylon fibers of the sheet and the collagen fibers, reducing the acidcontent of the suspension in said sheet to bring and maintain the pH tofrom about 3.5 to about 6.0 and removing the swelling water from saidfine short collagen fibers in the interstitial spaces of saidintermeshed fiber sheet to reaggregate them into a larger collagen fiberstructure within the interstitial spaces between the nylon fibersthroughout said sheet to reinforce the fibers of said sheet againstdisplacement, said reduction of acid content and removal of water beingeffected by treating said sheet with a volatile watermiscible organicsolvent, and thereafter tanning the collagen fibrous material with achromium tanning agent.

13. An open-fibered leather-like material comprising a mass ofintermeshed nonwoven fibers and associated collagen fiber structureextending through the interstices in said mass of fibers to reinforcethe fibers of said mass against displacement, said collagen fiberstructure possessing the special association with the fibers of saidmass secured by formation in situ in the interstitial spaces of saidmass of intermeshed fibers from an aqueous suspension of short distinctswollen collagen fibers of microscopic size by removing the swellingWater from the collagen fibers in the interstitial spaces of saidintermeshed fiber mass to reaggregate them into a larger collagen fiberstructure in reinforcing relation to the fibers of said mass.

14. An open-fibered leather-like sheet material comprising a mass ofintermeshed nonwoven fibers and associated collagen fiber structureextending through the interstices in said mass of fibers to reinforcethe fibers of said mass against displacement, said collagen fiberstructure constituting from about 5% to about 90% by weight based on thecombined Weight of the mass of fibers and the collagen fiber structureand said structure possessing the special association with the fibers ofsaid mass secured by formation in situ in the interstitial spaces ofsaid mass of intermeshed fibers from an aqueous suspension of finedistinct and swollen collagen fibers of microscopic size by removing theswelling water from the collagen fibers in the interstitial spaces ofsaid intermeshed fiber mass to reaggregate them into a larger collagenfiber structure in reinforcing relation to the fibers of said mass, saidcollagen fiber structure having a content of chromium combined intanning relation of from about 1% to about 3% by weight calculated as CRO based on the weight of the collagen fiber.

15. An open-fibered leather-like sheet material comprising a mass ofintermeshed nonwoven nylon fibers having a denier from 1 to 5 andassociated collagen fiber structure extending through the interstices insaid mass of fibers to reinforce the fibers of said mass againstdisplacement, said collagen fiber structure constituting from about 30%to about 50% by weight based on the combined weight of the mass offibers and the collagen fiber structure and said structure possessingthe special association with the fibers of said mass secured byformation in situ in the interstitial spaces of said mass of intermeshedfibers flOH'l an aqueous suspension of short distinct and swollencollagen fibers of microscopic size by removing swelling water and acidfrom the collagen fibers in the interstitial spaces of said intermeshedfiber mass to reaggregate them into a larger collagen fiber structure inreinforcing relation to the fibers of said mass, said collagen fiberstructure having a content of chromium combined in tanning relation offrom about 1% to about 3% by weight calculated as CR O based on theweight of the collagen fiber.

References Cited by the Examiner UNITED STATES PATENTS 2,040,511 5/1936Bleyenheuft 117-164 X 2,405,978 8/1946 Pickles 1l7--140 XR 2,838,3636/1958 Veis 106--124 XR 2,934,446 4/ 1960 Highberger et al. 162-15 1 XR2,934,447 4/1960 Highberger et a1. 162-151 XR 2,973,284 2/1961 Semegen117--138 XR 3,013,936 12/1961 Iyengar 117-l38.8 X 3,034,927 5/1962Fairclough et al. 117--140 3,071,483 1/1963 Tu 106155 3,073,714 1/1963Tu et a1 1174 XR WILLIAM D. MARTIN, Primary Examiner.

RICHARD D. NEVIUS, Examiner.

1. THE PROCESS OF FORMING A LEATHER-LIKE MATERIAL WHICH COMPRISES THESTEPS OF APPLYING TO AN INTERMESHED FIBER MASS IN PENETRATING RELATIONAN AQUEOUS SUSPENSION CONTAINING FROM ABOUT 1% TO ABOUT 5% BY WEIGHTBASED ON THE WEIGHT OF THE SUSPENSION OF SWOLLEN DISTINCT FINE COLLAGENFIBERS OF MICROSCOPIC SIZE TO CARRY SAID COLLAGEN FIBERS INTO THEINTERSTITIAL SPACES OF SAID INTERMESHED FIBER MASS, SAID SUSPENSIONHAVING A PH OUTSIDE THE ISOELECTRIC RANGE OF SAID COLLAGEN FIBER,REMOVING THE SWELLING WATER FROM SAID FINE SHORT COLLAGEN FIBERS IN THEINTERSTITIAL SPACES OF SAID INTERMESHED FIBER MASS TO REAGGREGATE THEMINTO A LARGER COLLAGEN FIBER STRUCTURE WITHIN THE INTERSTITIAL SPACESTHROUGHOUT SAID MASS OF INTERMESHED FIBERS TO REINFORCE SAID INTERMESHEDFIBERS AGAINST DISPLACEMENT.
 13. AN OPEN-FIBERED LEATHER-LIKE MATERIALCOMPRISING A MASS IN INTERMESHED NONWOVEN FIBERS AND ASSOCIATED COLLAGENFIBER STRUCTURE EXTENDING THROUGH THE INTERSTICES IN SAID MASS OF FIBERSTO REINFORCE THE FIBERS OF SAID MASS AGAINST DISPLACEMENT, SAID COLLAGENFIBER STRUCTURE POSSESSING THE SPECIAL ASSOCIATION WITH THE FIBERS OFSAID MASS SECURED BY FORMATION IN SITU IN THE INTERSTITIAL SPACES OFSAID MASS OF INTERMESHED FIBERS FROM AN AQUEOUS SUSPENSION OF SHORTDISTINCT SWOLLEN COLLAGEN FIBERS OF MICROSCOPIC SIZE BY REMOVING THESWELLING WATER FROM THE COLLAGEN FIBERS IN THE INTERSTITIAL SPACES OFSAID INTERMESHED FIBER MASS TO REAGGREGATE THEM INTO A LARGER COLLAGENFIBER STRUCTURE IN REINFORCEING RELATION TO THE FIBERS OF SAID MASS.